How to choose between 'that' and 'which' in your writing

The rules of grammar can seem complicated and rigid, but they will help you keep your writing clear and tell a story effectively. When the language is muddled, readers may get confused and quit reading.

Here are guidelines for choosing between that and which in a sentence.

The rule: Use which for clauses that offer incidental information; use that for clauses that give information necessary for the sentence. See how each changes the meaning of the following sentence.

The stream, which (incidentally, by the way) rises dangerously during flood season, flows near the village.

The stream that rises dangerously during flood season (as opposed to other streams) flows near the village.

The shortcut: If you could put the clause in parentheses or set it off with commas, use which. If the clause is needed to understand the sentence, use that.